Pearlbush shrub named &#39;Blizzard&#39;

ABSTRACT

‘Blizzard’ is a new pearlbush plant particularly distinguished by its compact habit, smaller plant height and width, larger flower diameter, and larger genome size.

GENUS AND SPECIES

Exochorda sp.

VARIETY DENOMINATION

‘Blizzard’

BACKGROUND OF THE NEW PLANT

The present invention comprises a new and distinct variety of Exochorda,botanically known as Exochorda sp., and hereinafter referred to by thevariety name ‘Blizzard’. This new pearlbush shrub was developed througha breeding program in Mills River, N.C. ‘Blizzard’ is an F₂ hybridbetween the female parent, Exochorda serratifolia (unpatented) and themale parent, Exochorda×macrantha ‘The Bride’ (unpatented). The firstasexual propagation of ‘Blizzard’ was carried out in the summer of 2003by rooting stem cuttings in Mills River, N.C. and has been asexuallyreproduced repeatedly by vegetative cuttings in North Carolina over a 7year period.

‘Blizzard’ roots readily from softwood cuttings from juvenile plantstreated with a basal dip of 5,000 ppm indole butyric acid (potassiumsalt) in water. ‘Blizzard’ has been found to retain its distinctivecharacteristics through successive asexual propagations via vegetativecuttings.

Plant Breeder's Rights for this variety have not been applied for.‘Blizzard’ has not been made publicly available or sold more than oneyear prior to the filing date of this application.

SUMMARY OF THE INVENTION

The following are the most outstanding and distinguishingcharacteristics of this new variety when grown under normalhorticultural practices at in Mills River, N.C.

1. A compact shrub habit;

2. Upright to rounded form;

3. Extremely floriferous with large flowers; and

4. A polyploid cytotype with a relative 2C genome size of approximately2.2 pg.

DESCRIPTION OF THE PHOTOGRAPHS

This new pearlbush variety is illustrated by the accompanyingphotographs which show the plant's form, foliage and inflorescences. Thecolors shown are as true as can be reasonably obtained by conventionalphotographic procedures. The photographs were taken in Mills River, N.C.

FIG. 1 shows a 6 year old, field-grown plant in full bloom in April,2008.

FIG. 2 shows the flowers of a greenhouse-grown plant in April, 2009.

DESCRIPTION OF THE NEW VARIETY

The following detailed description sets forth the distinctivecharacteristics of ‘Blizzard’. The detailed description was taken on6-year-old plants growing under landscape conditions in Mills River,N.C. in April 2008. Color references are to the R.H.S. Colour Chart ofThe Royal Horticultural Society of London (R.H.S.), 2001 Edition.

DETAILED BOTANICAL DESCRIPTION OF THE PLANT

-   Classification:    -   -   Botanical name.—Exochorda sp.        -   Common name.—Pearlbush.-   Parentage: An F₂ hybrid between the following parents.    -   -   Female parent.—Exochorda serratifolia (unpatented).        -   Male parent.—Exochorda×macrantha ‘The Bride’ (unpatented).-   Plant description:    -   -   Growth habit.—Compact.        -   Plant shape.—Upright when young, eventually becoming rounded            with age.        -   Height at maturity.—1.2 meters to 1.5 meters.        -   Width at maturity.—1.2 meters to 1.5 meters.-   Stem:    -   -   Mature stem color.—RHS N200A (Brown).        -   Immature stem color.—RHS 143A (Yellow-green).-   Leaves:    -   -   Type.—Deciduous.        -   Arrangement.—Alternate.        -   Shape.—Obovate to obelliptic.        -   Apex.—Obtuse mucronulate.        -   Base.—Cuneate.        -   Margin.—Entire but occasionally serrate towards the apex.        -   Mature leaf size.—Length: Average is 5.12 cm (range is 4.8            cm to 5.6 cm) Width: Average is 2.92 cm (range is 2.6 cm to            3.3 cm).        -   Immature leaf color.—Adaxial (upper) surface: Flushes RHS            143A (Green), which changes to RHS 137A (Green) Abaxial            (lower) surface: RHS 144A (Yellow-green) which changes to            RHS 137A (Green).        -   Mature leaf color.—Adaxial (upper) surface: RHS 137B (Green)            Abaxial (lower) surface: RHS 138B (Green).        -   Mature leaf texture.—Adaxial (upper) surface: Glabrous            Abaxial (lower) surface: Pubescent.        -   Leaf attachment.—Petiolate.        -   Petiole.—Shape: Moderately sulcate Length: Average is 0.55            cm (range is 0.47 cm to 0.62 cm) Width: Average is 0.096 cm            (range is 0.073 cm to 0.14 cm) Surface: Glabrous (not            pubescent).-   Inflorescence:    -   -   Inflorescence type.—Raceme with the occasional panicle.        -   Number of flowers per inflorescence.—4 to 10.        -   Flower diameter.—5.7 cm (range is 5.0 to 6.4 cm).        -   Type.—Perfect, simple.        -   Flowering season.—Early spring through late spring;            mid-April in Mills River, N.C.        -   Lastingness of flower on the plant.—7 to 21 days.        -   Fragrance.—Absent.        -   Length at anthesis.—Average is 6.0 cm (range is 3.6 cm to            8.6 cm).        -   Self cleaning or persistent.—Self-cleaning.        -   Petal.—Number of petals per flower: Average is 5 (range is 5            to 6) Color, adaxial (upper) surface at anthesis: RHS 155C            (White) Color, abaxial (lower) surfaces at anthesis: RHS            155C (White) Surface texture and appearance: Glabrous (not            pubescent), soft, thin and lustrous (slightly shiny) Shape:            Obovate Apex: Obtuse Base: Attenuate Margin: Irregularly            crenulate Length: Average is 2.36 cm (range is 2.13 cm to            2.67 cm) Width: Average is 1.29 cm (range is 0.93 cm to            1.44 cm) Petals, fused or unfused: Unfused.        -   Pedicel.—Shape: Cylindrical, laterally compressed Length:            Average is 0.37 cm (range is 0.15 cm to 0.81 cm) Width:            Average is 0.086 cm (range is 0.06 cm to 0.11 cm) Color: RHS            143A (Green) Surface texture: Glabrous (not pubescent).        -   Peduncle.—Shape: Cylindrical, laterally compressed Length:            Average is 1.19 cm from last flower to first pedicel (range            is 0.33 cm to 1.72 cm) Width: Average is 0.17 cm at base            (range is 0.14 cm to 0.20 cm) Color: Closest to RHS 143A            (Green) Surface texture: Glabrous (not pubescent).-   Reproductive organs:    -   -   Stamen.—Quantity per flower: Average is 31 (range is 28            to 36) Shape: Filament Color: Translucent RHS 155C (White)            Attachment: Dorsifixed Anther: Length: Average is 0.11 cm            (range is 0.082 cm to 0.137 cm) Width: Average is 0.063 cm            (range is 0.044 cm to 0.071 cm) Shape: Ovoid Color: RHS 11B            (Yellow) Pollen color: RHS 11B (Yellow) Pollen amount:            Moderate to copious, similar to parental lines.        -   Pistil.—Generally abortive.        -   Ovary.—Generally abortive or lacking.-   Fruit:    -   -   General.—Fruit are infrequent; when present, a coccetum with            5 fused carples.        -   Shape.—Flattened sphere.        -   Color.—Initially RHS 139D (Green) eventually turning 177D            (Brown).        -   Length.—1.2 cm.        -   Width.—1.5 cm.-   Seed: No viable seed have been observed.-   Disease and insect resistance: No significant disease or insect    pests have been observed.-   Genome size: The large flowers size of ‘Blizzard’ indicated that it    may be a polyploid. Flow cytometry was conducted to determine DNA    content which is directly correlated with ploidy level among closely    related taxa. Holoploid, 2C DNA content was determined on newly    expanded leaf tissue. Nuclei were extracted, stained with 4′,    6-Diamidino-2-phenylindole (DAPI), and analyzed (minimum of 5,000    nuclei per sample) using a flow cytometer (PA-I, Partec, Münster,    Germany). Pisum sativum L. ‘Ctirad’, with a known genome size of    8.75 pg was used as an internal standard. Mean (n=2), 2C DNA content    for ‘Blizzard’ was 2.2±0.003 (SEM) pg, approximately twice the DNA    content of either parent, indicating that ‘Blizzard’ is a polyploidy    cytotype (see Table 1).

COMPARISON WITH PARENTAL AND COMMERCIAL VARIETIES

‘Blizzard’ is distinguished from the female parent, Exochordaserratifolia (unpatented) in that ‘Blizzard’ has a compact habit, has asmaller mature plant height and width, has a larger flower diameter, anda larger 2C genome size than the female parent, Exochorda serratifolia.

‘Blizzard’ is distinguished from the male parent Exochorda×macrantha‘The Bride’ (unpatented) in that ‘Blizzard’ has an upright to roundedhabit, has a larger flower diameter, and larger 2C genome size than themale parent ‘The Bride’.

Table 1 shows the specific differences between ‘Blizzard’ and Exochordaserratifolia (unpatented) and Exochorda×macrantha ‘The Bride’(unpatented).

TABLE 1 Additional comparisons of ‘Blizzard’ with parental lines Taxa E.× macrantha Trait ‘Blizzard’ E. serratifolia ‘The Bride’ Flower diameter5.0 cm to 6.4 cm 2.8 cm to 4.5 cm 3.1 cm to 3.7 cm Petal number per 5 to6  5 to 11 5 or 6 flower Pistil Abortive Fasciated ovary Fasciated ovaryPlant habit Compact shrub Large shrub/ Open shrub small tree Plant shapeUpright/rounded Open/spreading Arching Plant height 1.2 m - 1.5 m 2.5m - 3.7 m 1.5 m - 2.5 m Plant width 1.2 m - 1.5 m 2.4 m - 3.7 m 1.2 m -2.4 m Relative Genome 2.2 ± 0.003 pg 1.1 ± 0.009 pg 1.2 ± 0.005 pg Size(2C DNA content ± SEM)

When ‘Blizzard’ is compared to the commercial variety E. serratifolia‘Northern Pearls’, ‘Blizzard’ is more compact with a upright/roundedform reaching approximately 1.5 m high, while ‘Northern Pearls’ has anarching vase shape and reaches 2.4 m.

1. A new and distinct variety of pearlbush shrub as described and shownherein.